The role of Palm Fronds Charcoal Waste Particles On Mechanical, Thermal, and Acoustic Insulation Properties of Epoxy Composite

The main objectives of the current study are to improve the mechanical, thermal, physical and sound insulation properties of an epoxy composite, in addition to reducing environmental pollution resulting from the burning of palm kernel waste, which results from annual periodic cleaning of the palms trees, which have been disposed of by burning it. Charcoal Waste Particles of Palm Fronds Base have been used for epoxy matrix as a naturalistic reinforcement particulate material, risk-free, and non-toxic to enhance its features. The charcoal waste particles have been used in weight rates of 0, 2.5, 5, 7.5, and 10%. As stated by the results, the reinforcement process by charcoal waste particles increased the tensile strength value from 8.78 MPa to 13.64 MPa, with a 55%, and increased the elastic modulus value from 0.67MPa to 3.63MPa, with a rate 437%. Moreover, additionally, increased the bending strength from 0.1MPa to 0.64MPa, with a 540%, the hardness value increased from 58.87 to 74 (Shore D No) with a rate 26%, as well as the wear rate has been decreased. Thermal conductivity has dropped by 30% from the pure sample’s value of 0.15W/m. °C to 0.11W/m. °C. Concerning the Acoustic insulation’s, the results demonstrate that the specimens decreased the transferred acoustic energy levels from 103.3 to 95.2dB with rate 8%, with regard to the density of the prepared specimens it has been decreased from 1.55g/cm3 to 1.35g/cm3 and the results show that the liquid absorption rates have been decreased for all composite specimens.


Introduction
Composites are materials that have been forming physically of two or more distinct phases with final product material merits better than the merits of the initial materials that produced these composites material [1,2].Composites are being used across various industries around the world, including in vehicles and panel equipment, frames, and other parts.Additionally, composites are also used in infrastructure applications such as buildings, roads, and bridges [3,4].Carbon composites have become a crucial component in modern technology, with numerous applications in military, civilian, energy, medical, and environmental fields.Polymer composites, made with affordable materials and equipment, are easy to produce and offer both process ability and cost-effectiveness [5][6][7].Composite materials are produced by combining or merging different materials or qualities in which the component elements are individually distinct, or, two or more phases combined physically, which result in a new material that has excellent features if compared to the features of the individual phases [8][9][10].In opposing to alloys, every phase of composites keeps its distinguished physical, mechanical, and chemical properties [9,11,12].The essential utilities of composites are good stiffness, high specific strength, and good electrical and thermal properties results.In addition to lightweights when they are compared with alloys or ceramics products [13,14].Composites can be classified according to the reinforcement's physical morphology as, fiber reinforced composite and particulate reinforced composite.In regards to the particulate-reinforced composite, it consists of very small particles, which have a reinforcement dimensions in microscales and nanoscales ranges [15][16][17].The features of polymer composites reinforced by particulate are controlled strongly by particle size, the adhesion of interfacial surface which separate reinforcement particle and the matrix molecules.Which means that the particle size has an evident influence on the final product features (composite) [18][19][20].Epoxy composites have many, diverse and different employments, particularly in high-efficiency, lightweight and low cost product, where a good mechanical merits are required.Epoxy implementations involve used these products in a particular parts of aircraft, boats, and vehicles, windmills [10,21,22].The composite mechanical features are controlled by the synergetic effect arising from multiple mechanisms, and these mechanisms are: (1) grain size refining, (2) residual stresses which lead to the thermal strains, (3) higher deformation densities and its restrictive motion at the interfacial surface which separate the reinforcement and the matrix [12,15,23].The ambition and the goal of the present research, are improving the mechanical and thermal features, in addition to the acoustic insulation by producing of polymer composite samples using the Palm Fronds Base Waste Charcoal Particles, (which is a by-product of the burning process waste of Palm Fronds Base Waste as a way to get rid of them, which increase of environmental pollution rates, in addition to it is also a haven for snakes, rodents, and scorpions that cause harm to humans and animals, and is also a good place for poisonous fungi).

Materials and method
Preparing the Palm Fronds Base Waste Charcoal Particles (PFBWCP) Where the waste of the palm was taken, Where the waste of the palm was washed, dried, and then burned for half an hour in a bowl, then it was placed in a bowl it containing water to extinguish it and remove dust and ash stuck in it figure 1, and then we grinded using then it was dried and an electric grinder several times until it reached a fine powder and was placed in the oven for an hour to get rid of moisture at a temperature of 70°C and the powder was flipping from time to time.The density of all composite specimens had been measured utilizing homemade equipment's, which is composed of a balance with 4 digits of, plastic bottle (a part of a plastic soft drink bottle has been cut) used to measure the mass of immersed samples, distilled water, glass stage to put the plastic bottle on it, and boiled potato masher with a plastic bottle cap attached to its top to measure the mass of samples in the air.The liquids absorption rates values were measured.This test has been carried using two of the most popular of the liquids detergent in Iraq (Fas and Lamis), where the liquid solution result has been mixed as one volumetric part of the detergent liquid to three volumetric parts of ordinary water used for household cleaning.The result solution has been placed in laboratory plastic containers (60 mm3) and the prepared specimens have been immersed in these containers every specimen alone.every reinforcing rate specimen have been divide into four groups 24h, 48h, 96h, and 192h, for every solution of the two detergent solutions, the weight of every specimen has been measured in air (before immersion) and after immersion, the liquids absorption rates has been calculated according to the following equation (1) [24][25][26].

Result and Discussion
This section presents the results obtained in this research regarding mechanical, thermal, acoustic and physical tests.In this section, we will review the results obtained in this research and analyse them scientifically.By looking at the X-ray diffraction diagram (Fig. 2) of the pure polymer sample, which is denoted by the symbol (P), and the sample of the charcoal powder used in the reinforcement process indicated by the symbol (PO), and the polymeric composite sample reinforced by the charcoal indicated by the symbol (PC).It can be observed that the epoxy material represents an amorphous phase, while the reinforcement powder represents a multiphase or (polycrystalline) material.As for the polymeric composite sample, the main phase was amorphous phase (epoxy).The regularity or crystallinity of the reinforcement particles affected the properties of the polymer, especially the thermal properties.Figure (3) illustrates stress-strain behaviour, all specimens initially exhibited elastic deformation, with an approximately uniform decrease in cross-sectional area with increasing sample length.Transmission from elastic distortion to plastic distortion occurs at yielding point.The specimens explain the cold drawing process.As explained, the pure sample exhibits high strain at and high elongation, but at low stress, where the breaking tensile or tensile strength is low compared with the specimens reinforced by the charcoal waste particles [27], the sample finally begins to fracture.However, these materials samples exhibit yield stress point and necking phenomenon.It can be clearly seen that with increasing the reinforcement rate, the strain ratio of the samples decreases, in other meaning the ductility decreases with the increase in the tensile stress value [27].
In other words, although the tensile strength value increased by increasing the reinforcement ratios, the value of the ductility of the samples decreased with the increase in the rate of the reinforcing process, which means that the reinforcement with particles transformed the composite material from ductility to brittle, but at the same time the reinforcing process increased the binding of the epoxy molecules with each other [28].This can be explained by the polymer chain breaking and voids and pores due to the mixing process of the reinforcement particles with the polymer during the mixing process and the reduction in chain mobility due to the interaction between the polymer and the filler [28].
The mechanical failure occurs (due to the external mechanical stresses) on the bonds in epoxy matrix as a result of the (and during) the growth of primary cracks caused by external mechanical stresses.In contrast to the state of the epoxy specimen (pure polymer specimen), the presence of reinforcing waste particles increases the energy absorption value and dissipation of the cracks in the composite materials sufficiently.However, when the polymer has been reinforced, all types of particles of reinforcement will store the great amount of the energy of the elastic stress of the composite material because it will support the major part of the applied load compared to the polymer (matrix material).These particles create barriers to fracture and stop or weakens the growth of small cracks that result from shocks, so the presence of the reinforcement particles in the composite material increases its resistance [24].
The effect caused from the breaking of the polymeric chains and the voids which have been originated by the existence of the reinforcement charcoal particles at the ratio of 25% was stronger than the binding or adhesion force between the reinforcement particles and the polymer particles resulted from the mechanical binding reinforcing rates.As a result, the pores and the voids were able to inhibit or diminish the binding forces, but the mechanical binding force raised with the reinforcement rates increasing until it reaches the maximum value at 0.1% [14].
It is also obvious that the reinforcing processes had increased the tensile strength value and decreased the ductility property of the reinforced composite specimens as a result of breaking of the polymeric chains and the brittleness nature of the reinforcing waste charcoal particles.
The waste particles reinforcement led to multiple effects simultaneously.The increase of binding forces amount, the number and area of interfaces between the particles of the reinforced material and the epoxy molecules (which increase with the increase of reinforcement rates) coincides with accompanied by a process of breaking the chains between the epoxy molecules, but in the result the binding forces will dominates, as they are the strongest, so the tensile strength increases.The following results can be concluded, the amount of thermal conductivity of the prepared composite specimens has been decreased due to the presence of pores and voids generated by the mixing process which led to separating polymer molecules, as a result of breaking the polymer chains bonds, which in turn led to preventing or restricting the movement of phonons, the responsible of the transfer of thermal energy within a material, the presence of voids causes a decrease in thermal conductivity However, the thermal conductivity increases gradually, but by a small amount, with the increase of the reinforcement rate due to the presence of carbon in the particles of the reinforcement material [17].We can infer from the results of the sound insulation that the process of reinforcing increases the sound insulation rates of the composite specimens when compared to the pure specimen (epoxy specimen).Due to the reinforcement particles' insulation features and their role as dispersal centres for the acoustic energy passing through the specimens, which reduces the transported energy to the opposite side of the specimen, which led to improve the acoustic insulation.In other words, the reinforcing particles increase the absorption, dispersion, and reflection of the energy in addition to the existence of the pores and voids resulted from the mixing process which lead finally to increase the sound insolation.As shown in Figure 11.For the reinforcing specimens with various weight ratios and the pure polymer specimen, the density has been measured using Archimedes method.As a result of the low density of the reinforcement material (coal) and the emergence of porous and voids during the blending process, the density value has been reduced as the reinforcement rates were increased, according to the results, where the density value of the pure specimen has been decreased from 1.557 g/cm3 to be 1.357 g/cm3 at the reinforcing rate 0.1%, as shown in figure 12. Humidity or the wetility of the liquids have a negative influence on thermal, mechanical, and physical features.The results of liquid absorption rates demonstrate that the voids and pores which have been created (as a results of reinforcing process) contributed to increase the rate of absorption of liquids [25], in addition to the natural tendency of charcoal waste particles to absorb liquids from the surrounding environment, and this led to an increase in the liquid absorption rates, however, the increase in absorption rate was very small, which is an excellent indicator that the specimens will be not considerably affected by liquids because they are planned to be used indoors.Figure 13 shows the influence of the reinforcing process on the results of the liquid absorption rates using Lamis and Fas detergents solutions respectively.

Conclusion
Experimental examinations have been carried out to observe the effects of Charcoal Waste Particles of Palm Fronds Base additives on the epoxy matrix and.Tensile, elastic modulus, bending strength, hardness, wear rate, the thermal conductivity, the acoustic insulation's, density, and the cleaning and sterilization liquids absorption rates, the results showed an improvement in most of the properties.The tests performed on the polymer with various weight rates of CWPPFB showed that the reinforcing of 10 % gave the best results.The reinforcement process significantly increased tensile strength, bending strength, hardness, and reduced ductility, as well the reinforcement process led to increased sound insulation, and this is an excellent indicator because it is planned to be used inside buildings.The reinforcement process led to a decrease in the thermal conductivity of the composite samples compared to the pure epoxy sample.This is also a positive result for the applications in which it will be used.Low density of composite samples due to the fact that the reinforcement material is a lightweight material as a result of the formation of pores and voids resulting from the reinforcement process.Finally, the percentage of water absorption increased with the increase in the percentage of reinforcement and the duration of immersion because they contain the largest percentage of carbon, which is water repellent.

Figure 1 .
Figure 1.Process of composite samples preparation steps.

Table 1 .
Weight percentage of charcoal particle, Tensile Strength, Young Modulus, and the matrix material.
Figure 13.The liquid absorption rates opposite immersion time, (upper) in Lamis liquid, (Lower) in Fas liquid.